Process for manufacture of chlorinated hydrocarbons



Patented Mar. 28, 1939 UNITED STATES PROCESS FOR MANUFACTURE OF CHLO- RINATED HYDBOCARBONS Wendell'W. Moyer, Syracuse, N. Y., asaignor to The Solvay Process Company, New York, N. Y., a corporation of New-York No Drawing. Application January 3, 1936, Serial No. 57,389

15 Claims.

This application is directed to an improved method of chlorination whereby the process is eflected in a highly efficient manner. a

The process of the present invention more particularly comprises chlorination of hydrocarbons and their halogen derivatives containing replaceable hydrogen or an unsaturated linkage in vapor (or gaseous) phase at elevated temperature by means of nitrosyl chloride. v

While treatment of hydrocarbons by means of nitrosyl chloride has previously been carried out experimentally, the processes employed have resulted in the formation of various materials in such admixture that the process has found no 16 practical application, the product in many cases being composed of resinous constituents of unknown composition apparently possessing no commercially useful properties. Consequently up til now direct chlorination has commonly been efzo fected by means of chlorine' It has now been found that under definite conditions of treatment, as more fully hereinafter disclosed, chlorinated products of controlled composition may be obtained in high yield by means of nitrosyl 25 chloride. Because of the highly exothermal nature of the reaction involved in chlorination by means of chlorine, this method presents difliculties with respect to satisfactory dissipation of heat and consequently with respect to uniform- 30 ity of reaction conditions. These dimculties are largely overcome by carrying-out the chlorination with NOCl as hereinafter more fully specifled.

The process of the present invention is espe- 35 cially adapted for continuous operation. Besides efiecting chlorination in an eflicient manner, the process yields nitric oxide, NO, as a byproduct. This by-product may be used to advantage in other processes.

40 In accordance with the present invention the organic compound to be chlorinated is reacted in vapor phase with gaseous nitrosyl chloride, NOCl, at a temperature above about 200 C. but below a temperature at which substantial thermal decom- 45 position of desired chemical structures occurs. The maximum temperature that may be employed in the process, of course, will depend upon the stability of the crude material and of the desired product and should not be sufliciently high to 50 eflect decomposition of these materials. For the chlorination of the more common hydrocarbons it has been found that temperatures up to around 500 C. may be employed, the preferred temperature range being from about 350 to about 425 5 C. The specific temperatures most favoring the reaction have been found to be somewhat higher in the case of aromatic than in the case of allphatic hydrocarbons. Thus temperatures around 350 C. are better suited for treatment of aliphatic compounds whereas temperatures in the 0 neighborhood of 425 C. are better suited for treatment of aromatic compounds.

The process has been found to be applicable generally to hydrocarbons or their halogen substitution products containing a replaceable hy- Q drogen or an unsaturated linkage, such as hydrocarbons of the aliphatic and alicyclic series, either saturated or unsaturated, to aromatic hydrocarbons, and'to hydrocarbons of the mixed aliphatic-aromatic type. 1

Alkanes and cycloalkanes may be chlorinated to form monoand poly-chlor-derivatives, thus methane may be chlorinated to form methyl chloride, chloroform, or carbon tetrachloride, ethane,

propane, butane, and pentane, and the higher chain hydrocarbons such as kerosene may be chlorinated to yield the mono, di, and higher polychlor-substituted products, and cyclohexane may be chlorinated to form monochlorcyclohexane.

Aromatic hydrocarbons, for instance benzene, naphthalene, diphenyl, etc,, and their homologues, also yield monoand polychlor derivatives, thus monoor di-chlor-benzene may be obtained by chlorination of benzene, and benzyl chloride, benzal chloride, and benzo-trichloride maybe obtained by chlorination of toluene. The process is especially applicable to efiecting chlorination of side chains inthe case of aliphatic substituted aromatic compounds such for example as toluene, but is also applicable to effecting chlorination of the aromatic ring.

The alkenes and alkines readily yield chlorderivatives by addition, for example ethylene yields ethylene dichloride, and from acetylene may be prepared the acetylene dichloride (di- 40 chlor-ethylene) and acetylene tetrachloride (tetrachlorethane) The monoand poly-nuclear hydro-aromatic hydrocarbons, for instance the cycloalkenes and hydronaphthalenes yield monoand poly-chlor derivatives when treated in accordance with the present process, thus from tetralin (tetrahydronaphthalene) may be formed the mono-chlor and poly-chlor derivatives, e. g. ac-chlortetrahydronaphthalene.

It will be evident that the process also may be used to advantage for the formation of higher chlorine derivatives from lower chlorine derivatives whatever method is employed in producing the lower chlorinated derivatives, and this is similarly true of the other lower halogenated derivatives-for example, dichlormethane may be chlorinated to form chloroform or carbon tetrachloride, and chloroform may be converted to carbon tetrachloride; likewise benzyl chloride may be chlorinated to form benzal chloride or benzotrichloride. 1

In order to elfect chlorination of hydrocarbons and their halogenated derivatives abovementioned by means of nitrosyl chloride in 'accordance with the present invention, it is mere- 1y necessary to mix the vapors of the material to be chlorinated with gaseous nitrosyl chloride and subject the mixture to a temperature above about 200 C. This may be eflected to advantage by passing the mixture through a heated reaction chamber, for instance a highly heated tube, the speed being controlled so that the material is raised to the required temperature in its passage through the heatedtube. Space velocities from 100 up to 1000 (cu. ft. of reaction mixture reduced to normal temperature and pressure) per hour per cu. ft. of reaction space) have been found to be advantageous. In general it has been found that higher temperatures tend toward more complete chlorination. Chlorination catalysts, for example metals ormetal chlorides, may be employed to assist the chlorination.

The ratio of NOCl to the compound depends upon the desired chlorination product, thus higher mol ratios tend to give more highly chlorinated products. The chlorinated products and the unconverted initial materials may be recovered in suitable manner. The separation process of course may be suited to the character of the compounds. Condensable products may be recovered by cooling the reaction gases. Unreacted nitrosyl chloride and hydrogen chloride formed by the chlorination may be separated from nitric oxide gas by scrubbing the gaseous reaction products with water. The nitric oxide may be further purified in suitable manner, and used in other processes, such as the manufacture of nitric acid. Unreacted initial materials may be returned in cyclic fashion for further treatment.

The following examples will serve to illustrate the method of carrying out the invention.

Example 1. Mo'nochlorbenzene.-Equimolar quantities of benzene and N001 in liquid form were mixed together at ordinary temperature. The mixture was then passed to a vaporizing chamber where it was vaporized to form an equimolar mixture of gaseous NOCl and benzene vapor. The gaseous mixture was passed continuously through an unobstructed tube heated to 425 C. The walls of the tube contacted with the mixture were composed of Pyrex glass. The space velocity of the total vapors was maintained at 2'70. The gases from the reaction tube were cooled to 20 C. by means of a water-cooled condenser fitted with an electrical precipitator to dissipate fog. The uncondensed gases were scrubbed, with cold water to remove HCl. The liquid reaction product obtained by the cooling step contained a quantity of monochlorbenzene equal to about 36% [of the benzene employed and a mixture of dichlorobenzenes corresponding to about 4% of the benzene employed. The rest of the reaction product consisted of unreacted benzene and a small quantity of tarry material.

Example 2. Benzyl chlorida-A vapor mixture of toluene and gaseous NOCl in equimolar ratio, produced in the same manner as in Example 1, was passed through a reaction tube heated to 350 C., the total space velocity being 100. 39%

benzyl chloride, benzal chloride, and benzotrichloride, 48% of the toluene being converted to the monochlor-, 27% to the dichlorand 24% to the trichlorderivatives.

Example 5. Carbon tetrachloride.-Gaseous methane and gaseous NOCl were metered into a mixing chamber in the ratio of 8.7 mols of NOCl to one mol of methane. The mixture was thn passed through a reaction tube heated to 400 C., a total space velocity of 100 being maintained. 57% of the methane was converted to carbon tetrachloride and 3% to chloroform. The rest was essentially unconverted CH4.

Comparison of the chlorination above with the corresponding chlorination with chlorine will serve to illustrate the advantages of the present invention from the standpoint of temperature control. The chlorination of methane to carbon tetrachloride by means of C12 liberates sufficient 7 heat so that the temperature of the reaction mix ture would rise nearly 2000 C. if cooling means were not provided to dissipate this heat. The temperature rise employing nitrosyl chloride as above outlined, however, in the absence of cooling means would be only about one-tenth of this amount. It is evident that not only may a great economy of cooling be obtained but, of still greater importance, accurate control of reacting conditions is made possible.

Example 6. chloroform-8 mols of NOCl were mixed with one mol of methane and the mixture passed through a reaction tube heated to 350 C. at a total space velocity of 150. 28% of the methane was converted to chloroform and 6.7% to carbon tetrachloride. The balance of the product was unconverted methane.

j Example 7. Amyl chloride.Equimolar quantitles of normal pentane and N001 in gaseous phase were thoroughly mixed and then passed through a reaction tube heated to a temperature of 350 C. at a total space velocity of 5'70. A yield of amyl chloride'corresponding to 27% of the pentane and of dichloro-pentane corresponding to 3.2% of the pentane was obtained. Except for a small loss in the form of tarry material, the rest of the pentane introduced into the reaction tube was recovered unchanged.

Example 8. DichZ0rethane.-An equimolar ratio of N001 and ethylene intimately mixed was passed in gaseous phase through the reaction tube heated to 300 C. at a total space velocity of 100. A yield of dichlorethane equal to 27% of the ethylene was obtained. The rest of the ethylene remained unchanged.

Example 9. Monochlornaphthalene.--Gaseous N001 and liquid naphthalene were introduced into a vaporizer in the ratio of 0.93 mol of N00! to one mol of naphthalene. The mixed vapor was passed through a reaction tube heated to 365 C. at a total space velocity of 100. 31% of the naphthalene was converted to mono-chloronaphthalene and 6% to dichloro-derivatives. Except for a slight loss due to tar formation, the rest of the naphthalene employed was recovered.

amass? Example 10. Cyclohezyl chloride.-Equimolar quantities of eyclohexane and NOCl in gaseous phase were thoroughly mixed and then passed through a reaction tube heated to a temperature or 350' C, at a total space velocity of 100. A conversion to cyclohexyl chloride corresponding to 23.6% of the cyclohexane and to dichloro-cyclohexanes corresponding to 3.9% of the cyclohexane was obtained. Some of the cyclohexane was converted to a. tarry material and the remainder was recovered- Example 11. Acetylene chlorides.-A gaseous mixture containing 4 mols of NOCl and 1 mol of acetylene was passed through a reaction tube heated to 350 C. at a space velocity of 100. A

conversionto tetrachlorethane (acetylene tetrachloride) corresponding to 7.5% of the acetylene and to the dichlorethylenes (acetylene dichlorides) corresponding to 21.6% of the acetylene was obtained. Some hydrogen cyanide also was found among the products.

I claim:

1. In the chlorination of a compound of the group consisting of hydrocarbon compounds and halogenated hydrocarbon compounds containing a hydrogen atom replaceable by chlorine and hydrocarbon compounds and halogenated hydrocarbon compounds containing an unsaturated linkage,the improvement which comprisespassing a gaseous mixture of the compound with nitrosyl chloride, in amount sufllcient to chlorinate a substantial proportion of said compound, through a reaction zone wherein it is heated to a temperature above about 200 C. and below the temperature at which substantial thermal decomposition of either the compound orchlorination product occurs at a space velocity between 100 and 1000 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

2. In the chlorination of a compound of the group consisting of hydrocarbon compounds andhalogenated hydrocarbon compounds containing a hydrogen atom replaceable by chlorine and hydrocarbon compounds and halogenated hydrocarbon compounds containing an unsaturated linkage, the improvement which comprises con tinuously passing a gaseous mixture of the com pound with nitrosyl chloride, in amount sufiicient to chlorinate a substantial proportion of said compounds, through a reaction zone wherein it is heated to a temperature above about 200 C. and below the temperature at which substantial thermal decomposition of either the compound or chlorination product occurs. at a space velocity between 100 and 1000 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

3. In the chlorination of a compound of the group consisting of hydrocarbon compounds and halogenated hydrocarbon compounds containing a hydrogen atom replaceable by chlorine and hydrocarbon compounds and halogenated hydrocarbon compounds containing an unsaturated 55 linkage, the improvement which comprises passing a mixture of the compound in vapor phase with nitrosyl chloride through a reaction zone wherein it is heated to a temperature between 200 C. and 500 C. at a space velocity between 100 and 7 1000 cubic feet of reaction mixture reduced to normal temperature and pressure per hour per cubic foot of reaction space.

4. The method of chlorinating a hydrocarbon, which comprises passing a vapor phase mixture 75 of the hydrocarbon and nitrosyl chloride, in

amount sumcient tochlorinate a substantial proportion oi said hydrocarbon, through a reaction zone wherein it is heated to a temperature between about 350 and. about 425 -.C., at'a space velocity between 100 and 1000 cubic feet of re- 5 action mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

5. The method of chlorinating a hydrocarbon,

which comprises passing a vapor phase mixture 10 ofthe hydrocarbon and NOCl in a ratio of at least one mol nitrosyl chloride for each moi oi. hydrocarbon through a reaction zone wherein it is heated to a temperature between about 350 C. and about 425 C. at a space velocity between 15 100 and 1000 cubic feet oi reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

6. The method of chlorinating an aikane, which comprises passing a vapor phase mixture of the alkane and NQC], in amount sufllcient to chlorinate a substantial proportion of said alkane. continuously through a reaction zone wherein it is heated to a temperature above 200 C. and below the temperature at which substantial thermal 25 decomposition of either the alkane or chlorination product occurs, at a space velocity between 100 and 1000 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space. 30

7. The method of chlorinating an aromatic hy-'- drocarbon, which comprises passing a vapor phase mixture of the aromatic hydrocarbon and NOCl. in amount sufiicient to chlorinate a substantial proportion of said hydrocarbon, continuously 5 through a reaction zone wherein it is heated to a temperature above 200 C. and below the temperature at which substantial thermal decomposition of either the hydrocarbon or chlorination product occurs, at a space velocity between 100 40 and 1000 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

8. The method of chlorinating a side chain of an aralkyl hydrocarbon, which comprises passing 5 a vapor phase mixture of the aralkyl hydrocarbon and nitrosyl chloride, in amount suflicient to chlorinate a substantial proportion oi said hydrocarbon, through a reaction zone wherein it is heated to a temperature above 200 C. and'below the temperature at which substantial thermal decomposition of either the hydrocarbon or chlorination product occurs, at a space velocity between 100 and 1000 cubic feet of reaction mixture, reduced to normal temperature and pressure, per 55 hour per cubic foot of reaction space.

9. The method of chlorinating pen'tane, which comprises passing a vapor phase mixture of the pentane and NCCl, in amount suflicient to chlorinate a substantial proportion of the pentane, co continuously through a reaction zone wherein it is heated to a temperature above 200 C. and below the temperature at which substantial thermal decomposition occurs; at a spacevelocity between 100 and 1000 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot 01' reaction space.

' 10. The method of 'chlorinating benzene, which comprises passing a vapor phase mixture of the benzene and N001, in amount sufiicient to chlorinate a substantial proportion of the henzene, continuously through a reaction zone wherein it is heated to a temperature above 200 C. and below the temperature at which substantial thermal decomposition occurs, at a space ve- II locity between and 1000 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

11. The method of chlorinating a side chain of toluene, which comprises passing a vapor phase mixture of the toluene and N001, in amount suflicient to chlorinate a substantial proportion of the toluene, through a reaction zone wherein it is heated to a temperature above 200 C. and below the temperature at which substantial thermal decomposition occurs, at a space velocity between 100 and 1000 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

12. The method of preparing amyl chloride, which comprises passing a vapor phase mixture of pentane and N001, in amount suflicient to chlorinate a substantial proportion of the pentane, through a reaction zone maintained at around 350 C., at a space velocity of around 570 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

13. The method of preparing monochlorbenzene, which comprises passing a vapor phase mixture of benzene and N061, in amount sufficient to chlorinate a substantial proportion of the benezene, through a reaction zone maintained at around 425 C. at a space velocity of around'270 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

14. The method of preparing benzyl chloride, which comprises passing .a vapor phase mixture of toluene and N001, in amount sumcient to chlorlnate a substantial proportion of the toluene, through a reaction zone maintained at around 350 C., at a space velocity around 100 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

15. The method of chlorinating a compound of the group consisting of hydrocarbon compounds and halogenated hydrocarbon compounds containing a replaceable hydrogen atom and hydro carbon compounds and halogenated hydrocarbon compounds containing an unsaturated linkage, which comprises preparing a vapor phase mixture containing more than about ten mol percent each of said compound and nitrosyl chloride, and passing said mixture through a reaction zone maintained at a temperature between200 and 500 C. at a space velocity between 100 and 1000 cubic feet of reaction mixture, reduced to normal temperature and pressure, per hour per cubic foot of reaction space.

WENDELL W. MOYER. 

